1. Field of the Invention
The present invention relates to a portable audio logic deck mechanism driven by a single driving source, and more particularly, to a logic deck mechanism for a portable audio whereby power consumption can be reduced by reducing the load applied on a main slide during a power switch and a mode switch and also varying the position of a pulley according to the mode to thereby control the tension of a belt.
2. Description of Related Art
A general portable audio deck mechanism is basically divided into a manual deck mechanism in which its head is manually operated, and a logic deck mechanism in which its head is automatically operated. The portable audio deck can record or reproduce information by employing a magnetic tape as a recording medium, and performs a head operation, tape traveling, and mode switching by the power of a single driving motor.
As shown in FIGS. 1 and 2, a conventional logic deck mechanism for a portable audio deck is comprised of a driving source 20 constituted of a single motor fixed to a main base 10, a power transmitting unit 30 for transmitting power from the driving source 20, a pair of reel tables 40 (see FIG. 2) on which the reels (not shown) of a tape cassette are safely loaded, an interlocking unit 50 interlocking with the power transmitting unit 30, for transmitting power to either of the reel tables 40, a magnetic head 60 for conducting magnetic recording and reproduction, a mode changing unit 70 for lifting and lowering the magnetic head 60 and changing the rotation speed and the rotational direction of the reel tables 40, and an ejecting unit 80 for loading and unloading the tape cassette.
The power transmitting unit 30 includes a pulley 32, a pair of capstan wheels 33 and 34, a main gear 35 engaged with the capstan wheel 34, and a belt 31 for connecting the driving source 20, the pulley 32 and the capstan wheels 33 and 34. Accordingly, the rotating force of the driving source 20 is transmitted to the main gear 35.
The interlocking unit 50 includes a plurality of gears, and drives the reel table 40 using the rotating force transmitted through the main gear 35.
The mode changing unit 70 includes a cam gear 71 having a cam groove 71a, which selectively rotates by being engaged with the main gear 35, and a main slide 73 having a protrusion 73a to be combined with the cam groove 71a. The main slide 73 changes the operating mode by being linearly moved by the rotation of the cam gear 71.
The magnetic head 60 is installed on a head slide 61, and ascends and descends in engagement with the main slide 73.
The ejecting unit 80 is comprised of a switch knob 81, an eject slide 83 and lever members 85 and 87. In a still mode, the motion of the switch knob 81 opens a door (not shown). In an operating mode, the lever member 87 is caught in a stopper 74 installed on the main slide 73, so that opening of the door is prevented. Also, the head slide 61 may be selectively caught within a groove 83a on the eject slide 83, thereby performing an automatic music sensor (AMS) operation.
In the conventional portable audio logic deck mechanism having such a configuration, mode change, pivoting of a pinch roller, and raising and lowering of the magnetic head 60 are accomplished by the linear motion of the main slide 73. Thus, overloads are applied on the cam gear 71 for transferring the main slide 73.
The eject slide 83 and the lever member 85 must be additionally included to lift and lower the magnetic head 60 according to the movement of the main slide 73. A function of preventing the opening of the door is conducted separately with the AMS function in a play mode. Thus, the structure of the mechanism becomes complicated, and a large number of components is required.
Furthermore, the pulley 32 and the pair of capstan wheels 33 and 34 are rotatably fixed onto the main base 10, so it is impossible to vary the tension of the belt 31. That is, the tension of the belt 31 is always constant to be appropriate for the greatest load regardless of forward or reverse direction play modes, a high-speed winding mode, a still mode, etc. Therefore, the load applied to the power transmitting unit 30 is large even when a small load is needed as in the play mode, which wastes power.